onsemi’s MCU Backs Up Power Efficiency “Industry Record” With EEMBC Benchmark

December 01, 2021 by Jake Hertz

Record-breaking and "world's first" announcements happen every day. Hoping to back up its "record-breaking" power efficiency claim, onsemi's MCU, targeting IoT applications, goes through official benchmarking.

In today's world of embedded computing, power efficiency is arguably the most important thing a microcontroller unit (MCU) can bring to the table. This need has led to many companies continually pushing state of the art in terms of power efficiency, with many of them continually claiming "industry firsts" or "best in class" performance. 

Sometimes it can become hard to differentiate between clever marketing and genuinely impressive products. The latest company to claim an industry record for power is onsemi, which announced its RSL15 Bluetooth low energy (BLE) MCU earlier this week. 


A representation of onsemi's RSL15 MCU.

A representation of onsemi's RSL15 MCU. Image used courtesy of onsemi


In this article, let's take a look at the new MCU and try to decipher if it's really an industry record in power efficiency or just another stepping stone in advancing MCUs to the next level. 


onsemi's RSL15 Microcontroller

This week, onsemi's newest offering came in the form of its RSL15 wireless MCU

This new MCU was designed to be an ultra-low-power, high-security processor incorporating BLE 5.2 connectivity. To achieve this, the MCU offers a solid level of integration, including a: 

  • 48 MHz Arm Cortex M33 core
  • Built-in power management circuitry
  • RF (radio frequency) subsystem

The RF subsystem features a 2.4 GHz frontend, low-power low noise amplifiers (LNAs), power amplifiers, and more. 

All in all, the system comes with 80 KB random access memory (RAM), up to 512 KB of Flash, and an internal direct memory access (DMA) controller for background transfers between peripherals and memories without intervention.


Detailed block diagram of the RSL15.

Detailed block diagram of the RSL15. Image used courtesy of onsemi


Beyond these blocks, the RSL15 also prioritizes security, integrating Arm TrustZone technology along with Arm CryptoCell-312 technology. Together these two enable the RSL15 with hardware and software level security, including secure executions and code authenticity. 

In terms of power consumption, this MCU features a variety of sleep modes reaching power consumptions as low as 36 nA with GPIO Wakeup drawing from a 3 V battery. At 3 V and a 1 Mbps data rate, the MCU reaches peak RX and TX currents of 3 mA and 4.3 mA, respectively. Overall, onsemi claims that both the active and sleep power specs provide them with industry records. 


EEMBC's ULPMark Benchmark 

One way to validate its energy efficiency claims, onsemi turned to the Embedded Microprocessor Benchmark Consortium (EEMBC).

The EEMBC, a group that develops industry-standard benchmarks for embedded devices, utilizes several benchmarks to quantify power efficiency. The benchmark which onsemi claims to be a record is its ULPMark benchmark, a benchmark that quantifies many different aspects of ultra-low-power MCUs. 


The RSL15’s ULPMark benchmark score table.

The RSL15’s ULPMark benchmark score table. Image used courtesy of EEMBC


The results of its benchmarking prove that the RSL15's claim to the industry record is not just a gimmick but is indeed substantiated by external benchmarking. 

The RSL15 scored a class-leading 'performance' score of ~60.5 on the ULPMark-CoreMark benchmark, which measures the energy efficiency of MCUs while active. This score represents a record in Bluetooth 5.2 efficiency. Equally as impressive, on the ULPMark-CoreProfile benchmark, which calculates the deep sleep efficiency of MCUs, onsemi now claims the top two rankings in its class with the RSL15 and RSL10, respectively. 


Closing Thoughts 

In a world where marketing strategies and real technology can be hard to differentiate between, it seems that onsemi's RSL15 has emerged as a genuine, impressive piece of technology. 

As validated by the EEMBC, the RSL15 offers industry records in Bluetooth 5.2 performance, making this device highly applicable in many low-power applications such as the internet of things (IoT).



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